target/riscv/cpu.c: add riscv_cpu_add_kvm_unavail_prop_array()

target/riscv/cpu.c: add riscv_cpu_add_kvm_unavail_prop_array()

Use a helper in riscv_cpu_add_kvm_properties() to eliminate some of its
code repetition.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20230912132423.268494-9-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>